He's got a lovely bunch of . . . loosely bunched grapes

July 11 2003By Tom Noble

How do you stop botrytis fungus from invading grapes before the wine harvest? Make the grapes grow in looser bunches.

CSIRO scientist Yuri Shavrukov says that by next year he hopes to identify the gene that makes some grape varieties produce their fruit in bunches that have plenty of air between the grapes -such as sultanas - rather than densely packed varieties such as chardonnay and riesling.

"Every year the grape industry loses a lot of product," he says. "It depends on the climate. If it is cold and rainy, which happens often, it means a lot of lost product. Four years out of five, mostly in South Australia but also in Victoria, it is a problem."

"In South Australia at harvest time when it is wet and not so hot, it is good conditions for botrytis rot to attack and develop inside bunches," he says. "It's a problem."");document.write("

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The project for the CSIRO horticulture unit in South Australia is to examine other grape varieties, including the sultana and exotic, which produce grapes in looser bunches.

"If you take this gene that controls looseness and put it into riesling and chardonnay . . . and don't touch the quality of berries so the wine is not affected," he says, "there will be no need for treatment with chemicals and fungicides. So the environment will be cleaner."

Two years into the three-year project, Dr Shavrukov says they have found the area where the gene appeared to be. "That is several more steps, then we will have success. Genetically it is not such a problem."